In this guide
Vitamin D helps the body use calcium for bones and supports muscles. Tiredness or aches have many possible causes, so symptoms alone do not prove a deficiency. This is general information, not treatment advice.
How a deficiency is confirmed
Status is assessed with a 25(OH)D blood test. Cut offs can differ between guidelines, so ask your doctor how they read your result. Higher risk groups include older adults, people with darker skin, those who spend little time outdoors and people with digestive disorders or obesity.
Everyday sources
- Sunlight: short exposure in summer, while protecting skin from burns.
- Food: oily fish, eggs and fortified products.
- Supplements: only when a doctor or dietitian recommends them based on your result.
Be careful with doses
Too much vitamin D from supplements can raise blood calcium and strain the kidneys. The upper limit for adults is 100 micrograms (4,000 IU) a day from all sources. Do not exceed it without medical supervision.
What to ask your doctor
- Do I need a test, and how does my result compare with the target?
- Do my medicines or conditions affect vitamin D?
- What dose, for how long, and when should the test be repeated?
Before your appointment write down when your symptoms began, which medicines and supplements you take and how much time you spend outdoors. If you already have an earlier result, bring it for comparison. This helps the doctor judge whether you need a test or a change of habits.
Common questions
Can I decide my own vitamin D dose?
Better not. The dose depends on your result, medicines and conditions, and too much can be harmful.
Are tiredness and muscle aches proof of deficiency?
No. They have many causes, so you need a doctor assessment and a test.
Before first use
Choose products for your dietary routine and care needs. Follow a healthcare professional’s advice for diagnosis and treatment of symptoms. Check suitability first during pregnancy and for use by children.
